Syringe



Nov. 13, 1951 J. ElSNSTARK SYRINGE Filed June 24, 1949 INVENTOR.

BY JIM U5 E/SENST/IKK A TTORNE Y Patented Nov. 13, 1951 g fThis 'inventionprelates to an improved hypo 1 dermic syringe of thetype used by-physicians,; dentists, nurses, research workers and other membersof the medical and allied professions.

A ,Hypodermic syringes are exceedinglydelicate instruments. They are generally made of glass and they break with disturbing frequency during the process of their'manufacture, as well as in use, and especially during theprocessof sterilizing them. Another disturbing element in their construction is the presence of closed corners which are difiicult to reach for cleaning and sterilizing purposes; 'With all these disadvantages, there is the added factor of high cost resulting from their-complex structure and the difficult manufacturing processes which are required to produce them. v

The hypodermic syringe comprising the present invention possesses none of these disadvantages. In the first place, it is made of a practically inert plastic material that withstands boiling or steaming in the sterilizer and which is unbreakable under conditions of normal use. In the sec- 0nd place, it is wholly devoid of dead-end or closed corners socommon to conventional syringes and so hard to reach- It is accordinglythe principal object of this invention to provide a hypodermic syringe which ismade of relatively unbreakable material and which is accessible in all of its parts for cleaning and sterilizing purposes. More particularly, the barrel, neb and plunger are all made of plastic material such as polystyrene (P-B-polystyrene made by Koppers Coke go.).- The barrel, the plunger and the neb are all readily detachable from each other; The barrel is a tubular member without end walls. Even the plunger may have a detachable piston. All of the parts, therefore, are readily accessible forcleaning purposes.

Another important object of this invention is the provision of a hypodermic syringe in which the plunger, and moreparticularly its piston, is tapered to cone shape and the piston seat is tapered correspondingly. Marked advantages flow from this construction. Principally, this tapered design makes forgreater accuracy, especially for injecting medicaments in small amounts. Another important advantage resides in the fact that this design renders the material of which the several parts of the syringe are: made, suitable for extrusion processes. Furthermore, the tapered design makes it possible to empty the syringe to a virtually microscopic extent, leaving only that small quantity of medica 3 Claims. (01. 128-218) g L this tapered design makes for very fine gradations and correspondingly fine measurements of the dispensedmedicament.

A further object, of this invention is the pro vision of a hypodermic syringe of the character described which is virtually leak-proof in all of;

the areas of contact between itsmoving parts, irrespective of the viscosity of the medicament or other liquid preparation being dispensed.

A still further object of this invention is the provision of a hypodermic syringe of the character describedwhich isreadily demountablefor cleaning and-other purposes and which is equally.

as readily reassembled for use. The several parts are so designed that there is little danger of -con-; faminating its inner critical surfaces by haniling-them following their exposure to heat during the, sterilizing,..process.

Preferred forms of this invention are shown in the accompanying drawing, in which:

Fig.1 is a side view ofa hypodermic syringe made in accordance with the first form of this invention. Y V I Fig. 2 is a longitudinal .section through the barrel thereof. Y

Fig. 3 is a rearend view of said barrel. Fig. 1: is an. exploded, view in longitudinal section of the neb andneedle holder, the needle itself being shown mountedin said needle holder, partly in section.

Fig. 5 is an end view in, said view being inathe. direction of arrows 5-5 of Fig. 4.

thereof is mounted thereon.

Fig. '7 ,is a fragmentary longitudinal section through the hypodermic syringe shown-in Fig. l and through'the parts thereof shown inFigs. 2, 4 and 6, saidpartsbeing shown in assembled and operative positions. 7 I

Fig. .8 is aviewsimilar to that of Fig. 7 of a hypodermic. syringe made in accordance with a second form of this invention, showing a different mountingfor theneedle, a diiferent method of attaching the piston to the'stem of the plunger, and a different method of-attaching the neb to the barrel. v

A syringe madein accordance'with the present inventionincludes abarrell0, aplunger ll having a piston l2, aneedle IS -mounted in a needle holder I4 and a neb-l 5 by'which the needle holder is secured to the barrel. As has above been ment which occupies the needle. And finally, 66 stated, barrel Ill is tubular in shape, and it has endot said needle holder, showing theineedle mounted there-.

disintegrate in the presence of sufficient heat to sterilize it or of medicaments it is filled with, and

also which is strongly resistent to breakage? Nylon, for example, is highly suitable for the purposes of the present invention. Sb ispoly:

I2. Neb I is a collar-like member which has a tapered top wall 35 having a central opening 36 through which the needle projects when the neb is mounted on the barrel as shown in Fig. 1. It has a bayonet slot 31 which is adapted to engage pins 23 on the barrel to secure said neb to said barrel and hence the needle holder and needle to the barrel. The taper of its top or forward wall 35 again corresponds to the. tapered partsaboveidescribed, and hencel; wlrfen the neb is mounted on the barrel, anda 's'iiug fit is provided between its said wall 35 and the top shoulder of needle holder I4 as well as between seat "32-'of the needle holder and tapered edge 24 of the barreL- Longitudinally extending openings STE-are" pi ovided in the side wall of neb I5 to styrene such as polystyrene-8 of the Kop'p'eis Cc'ike' Co., Styron of the Dow Chemical Co., Lustron of tucl; Chemical Co. I

Plung'rll iri'ai v :ififi-ohs'iifiilr material: l t cb'mprfs'e s a sha ft i--'siteni*-having a1- button 21 formed at its back v fid being re dfi''d'at its forward end to a 's'iriiall externally threaded end" portion 28; Piston" I 2'i'has molded" integrally an internal' 9 bushing 29 which may-Be made of metal; and sa-iutush ng is internally threaded 'to receive the eateriiaiiy threaded-I61 ward end portiori- 23 of tfie plunger. Piston I2" is somewhat'larger ih dia 'ete'r than" the shaftf'pi the plunger, ar'i'dits d i'e'virriete1"c o'rfres'ponds t'o the inside-diameter ma oit fib i -f-iiai ei- Ill-. Ase'rles of annular grooves 3911s formeddn' theouter" curved wall s iirf aceoffthe piston dia plurality orj annular" ridges" or bands is'jthe'reby defi'n'e'd-I This-makes for a relatively flexible outer wall surface or contact area which engages the'inner wall of the barrel. Ifdesirektring-shape'd washers made Qfsviithetic rubber jor 'oth'er suitable material may befmourftedinthefannulargrooves for-an" enhanced "leak proof seal 'between the' piston and the barrel.

eizposethexcalibrations 38 which are provided on barrel I0.

, It will be noted that the/forward end ofpi s'ton" I fT'iS tapered tdtlie sli'fib fifa 60116; TIYB ajngle of this cone corresppnds to the angl of taper of peripheral 'e'dgifof 'rie'l' I0? ltalso corres oiids "tn the tater" ofjpistiii eat' 9'2 vvhi'ch' is forme ontiie-mmrnrtacnehdtr fieedl e Home? l4? conseaueiitiyc when the" nee le order is" mounted tightly upon tapered edge 2 f of th bairei by'the 'meanshereinafter"describ d; a'lalgfii'hof Seal is pr vides be'b'filfi Said n 'edl'fidl'di and saidbarrel. Also? when thpiston ismdvd" into abutment with its said seat 32 everv last" nieasnrable' ouantitv of lid1 id'' i SQSGIlPGZQCI or pressed out of "the barrel and nit thnee'dlel' The taper shown theidfawiii f'is approximatelv removed from theflongit d nalaxis Of the instrument andWh SPsbOiildbe taken" as illust tive and not as" limitati've o'f'the present invention) A more acute amie; wou d make for greater accuracy and more pre iseme'asuremehts as Well as fdr greater (lbfitidldVGrWheinStiumeat d rifi 'dis'i Theieasorri'sfici ar: tiie'inore acutethe anciedlj'fiajii"; the: greaterwiii Be the stroke 'M h s filmigr to" dispense or eject a giveri'n'uarjtityOfflitl'liiti; 1

. Needle- I3 'is set-in" ne lho d i I4 5v means" of a rubber gasket 33 or the like. The-holder pro er" I 4 ispe'rfofated as at I M to enable the rubberto' new inta-thea irfora-tidm and be anchored: firmly" therein; The to shou der of" holder H is also tapered fo th extent above iii"- dicated' with respect tweet-32; peripheral dg N -of barrel 1 IU and -th foiward end of pistbn 7'6 master haVing-a-cntraT opriing forihedthrethe first-form of this" invention, theneb 'maybe made or plastic-material or metar as desired: the present, second form of thiirvntioh; the net must'be'ma'de' o'f-metalif the needle is-to" be to ii in and having a needle secured thereto in said opening, said piston-seat member and the adjacent portion of said needle having a continuous covering of resilient material.

2. A hypodermic syringe comprising an openended tubular barrel, a plunger slidably mounted in said barrel, a tapered piston mounted at the forward end of said plunger and having a tapered leading end, a neb removably mounted at the forward end of said barrel, and a needle holder secured to the forward end of the barrel by means of said neb, said needle holder having a needle secured thereto and projecting forwardly therefrom, and having a piston seat formed thereon at its inner end, said piston seat being tapered to correspond to the taper of the piston, and a covering of resilient material enveloping said needle holder and the portion of said needle adjacent thereto.

3. A hypodermic syringe in accordance with claim 2, wherein the neb is demountably secured to the forward end of the barrel by means of a pin which is provided on said barrel and a cooperating bayonet slot which is provided in said neb.

JULIUS EISENSTARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 596,159 Haycock Dec. 28, 1897 600,803 Robinson et a1 Mar. 15, 1898 650,203 Stovall May 22, 1900 1,453,418 Tessmer May 1, 1923 1,648,135 Klett Nov. 8, 1927 1,782,938 Pletcher Nov. 25, 1930 1,948,982 Cutter Feb. 27, 1934 1,987,146 Hein Jan. 8, 1935 2,361,617 Everett Oct. 31, 1944 FOREIGN PATENTS Number Country Date 580,185 Great Britain Aug. 29, 1946 632,883 Germany July 15, 1936 

